Preheat your oven to 180C | 160C Fan.
Grease and line a 26cm | 10in cake tin.
Mix all the dry ingredients (except carrot and walnuts) in a large bowl until combined.
Gradually add 450ml oil and 5 eggs until combined.
Stir in 525g (about 4) carrots and 150g walnuts.
Pour your mixture into your cake tin and bake for 1 hour and 30 minutes. Check to see if it’s ready by inserting a skewer into the centre - it should come out clean. If there’s still gooey mixture in the middle then bake for a further 15 minutes.
Remove the cake from the oven and cool in the tin for 10 minutes.
Carefully remove the cake from the tin and cool completely on a cooling rack.